In the simplex/duplex copier disclosed in commonly assigned U.S. Pat. Nos. 4,095,979, issued June 20, 1978 and 4,174,905, issued Nov. 20, 1979, both of which are entitled "Method and Apparatus For Producing Duplex Copies", first and second toner images are formed on a moving photoconductive belt and are transferred to the opposite sides of a copy sheet. Located along the photoconductive belt are a first image transfer station for transferring the first toner image from the belt to one side of a copy sheet, a copy sheet inverter for inverting the copy sheet after first image transfer and a second transfer station for transferring the second toner image from the belt to the other side of the copy sheet. A sheet registration device is provided in advance of the first transfer station to register either simplex or duplex copy sheets brought into contact with the photoconductive belt. When simplex copies are made the copy sheet passes under both of the transfer stations.
Commonly assigned U.S. Pat. No. 4,194,829, issued Mar. 25, 1980, entitled "Apparatus For Producing Duplex Copies" discloses apparatus for producing duplex copies in which a registration device is located between a sheet inverting belt and a second transfer station to register inverted duplex sheets. The device does not register simplex sheets.
Commonly assigned U.S. Pat. No. 4,158,500, issued June 19, 1979, entitled "Apparatus For Producing Collated Copies In Page Sequential Order"; Research Disclosure ("Research Disclosure" formerly "Product Licensing Index" is published by Industrial Opportunities Ltd., Homewell, Havant, Hampshire, U.K.) No. 17,579 published November, 1978, entitled "Apparatus For Producing Duplex Copies"; Research Disclosure No. 18,446 published August, 1979, entitled "Copy Sheet Diverter"; and Research Disclosure No. 18,546, published September, 1979, entitled "Copy Sheet Diverter" disclose duplex apparatus wherein copy sheet diverters are located between a copy sheet inverting belt or drum and a photoconductive belt to assist in guiding a copy sheet carrying a toner image on one side back into contact with the belt for subsequent transfer of a second toner image to the other side of the copy sheet. No registration mechanism is associated with any of these diverters.
Commonly assigned U.S. Pat. No. 4,191,465 issued Mar. 4, 1960, entitled "Apparatus For Producing Simplex or Duplex Copies"; Research Disclosure No. 17,438 published October, 1978, entitled "Apparatus For Producing Duplex Copies"; and Research Disclosure No. 18,553 published September, 1979, entitled "Control For Duplex Copier" disclose copy sheet diverters used in conjunction with copy sheet inverters to guide copy sheets along the same path in both the simplex and duplex mode. No registration devices are operatively associated with any of the disclosed diverters.
Commonly assigned U.S. Pat. Nos. 4,019,732 and 4,019,733 both of which issued Apr. 26, 1977; and both of which are entitled "Sheet Registration Mechanism"; Research Disclosure No. 18,270 published June, 1979, entitled "Registration Gate Mechanism For Recirculating Document Feeder and Document Positioner"; and Research Disclosure No. 17,322 published September, 1978, entitled "Apparatus For Registering and Feeding Documents" disclose various types of latchable registration mechanisms.
Although the disclosed sheet registration devices and diverters may be suitable for the purposes for which they were intended, none are concerned with providing apparatus for guiding copy sheets along two paths which converge and for registering a copy sheet moved along one of these paths near the region of convergence and of holding the registration device out of either path when a copy sheet is moved along the second path. More particularly, none are concerned with providing apparatus in simplex/duplex reproduction apparatus wherein in the simplex mode sheets are guided along a first path and registered just in advance of a toner image transfer station located adjacent to an image transfer member and wherein in the duplex mode copy sheets are guided along a second path which converges with the first path in advance of the transfer station. It is desirable to register copy sheets as close to the transfer member as possible to minimize skewing of the sheet between registration and contact of the sheet with the toner image carrying transfer member.